Hi all,

I was just thinking with most if not all airlines going with 2 engine
widebodies a la 777/787/350.....etc I was wondering are the days of Boeing and
Airbus done producing anymore 4 engine widebodies after the A380
B744/748 are done on thier respective production lines?

Hi Mia
It seems so.
In the harsh aviation business it (nowadays) all comes down to costs. Now there are a couple of basic factors to consider:

first will hopefully always stay safety. In the old days of piston engines 4 was better than two, because one would always pack up. Today the reliability of a modern engine is much higher and can be disregarded as a safety feature (ETOPS) in choosing 4 over 2 engines.
Then , of course, the engines have developed so much- the power output of a modern two-holer is so much more than of a old 4-holer.

second is cost of the airframe, fuel consumption, maintenance and so on.

third factor is capacity- do the airlines need planes (new designs other than 380, 748) which carry 500+ pax? Will the market buy these planes which makes it worthwhile to build a new one?

All this is very debateable, but at the moment it seems very much in favor of new two-holers rather than 4.

This is a thread to give the usual pack a field trip...

Quoting art (Reply 5): That is what I expect to happen on a lot of routes in the future.

Certainly. The A380 entered the market just as volume slowly begins to warrant planes of its size. At first it will be relevant only for a few routes and for a few airlines. But as traffic is doubling every 15 years, that will change little by little unless one sincerely believe that the world's main hubs can handle the double number of movements compared to what we see today. And as the 380 has captured this segment (Boeing is not going to develop anything new in the foreseeable future after the 787 fiasco), Airbus holds what will become a very lucrative position as aircrafts are priced not according to what they cost to build but according to the revenue they can generate for the airlines.

Technology permits A & B should look into in-flight engine shutdown/re-lit option. This was discussed on other threads and lot of unanswered questions like

Is it possible to cruise with n-1 or n-2 engines?
Are there any altitude restrictions for engine re-lit?
Will it be still economical with n-1 or n-2 engines running?

Otherwise VVIP transportation is the last market for new ones. Quite a few nations still not convinced to use twin engine aircraft for their leaders. Existing birds will survive as Freighters for a long time.

Quoting abba (Reply 7): This is a thread to give the usual pack a field trip...

Yes, its a matter of time until our Austrailian friend with his friendly attitude towards the A380, 4 holers in genaral and Airbus will educate us with his lesons again. 
I will check if I have enough popcorn in stock 

Quoting abba (Reply 7): Quoting art (Reply 5): That is what I expect to happen on a lot of routes in the future. Certainly. The A380 entered the market just as volume slowly begins to warrant planes of its size. At first it will be relevant only for a few routes and for a few airlines. But as traffic is doubling every 15 years, that will change little by little unless one sincerely believe that the world's main hubs can handle the double number of movements compared to what we see today. And as the 380 has captured this segment (Boeing is not going to develop anything new in the foreseeable future after the 787 fiasco), Airbus holds what will become a very lucrative position as aircrafts are priced not according to what they cost to build but according to the revenue they can generate for the airlines.

I expect it the same. The market will slowly increase in average size planes. At the same time seat density may lower if Economy + concepts turn out to be a business for Airlines, requiring larger planes for the same number of people.

Airbus has spent the development cost for the A380. Everything is booked in the financials. No 'accounting block' in European accounting standards.
With 4 Engines, the A380 can use every 10 -15 years the newest engine technology developped for the midsize Widebodies with high volume outputs to be up to date with moderate costs for A380 airframe integration. This should be enough to keep the A380 CASM leader with a step development down every 12 years. First re-engine will be 1-3 years after the 777x comes to market (2020-2022), getting at least the same engine technology then.

If Market really has high demand allowing more investment to spend they can 're-wing' and otherwise modernize the A380 in a further step (20130?) - much similar as Boeing intends to give the 777 a future in shape of the 777x.

Boeing will not have a business case to develop a totally new 500-600 Seat plane with todays development cost levels. It would need dedicated larger (rather low volume) engines (of course 2 then) and Airbus would neither..

So the 4 holer in shape of the A380 will continue to exist, volumes will increase slowly but steadily.

Regards

Flyglobal

Quoting art (Reply 5): Re: size, I note that EK are switching service to Brisbane from 777 to A380 because the route requires more capacity. That is what I expect to happen on a lot of routes in the future.

by which you mean EK has so many on order it doesn't know what the hell to do with them all right? BNE was always a candidate as a large city with an isolated population, but as more of them get delivered there will be more and more of them going to airports that don't need that capacity at all.

Quoting aerorobnz (Reply 10): as more of them get delivered there will be more and more of them going to airports that don't need that capacity at all.

Relative to this rather general and imprecise statement – indicating that you know EK and EK’s business model better than EK themselves - would you care to give some examples as to which routes EK is using their 380s where they don't have the demand and where they could have used other frames more economically?

Quoting flyglobal (Reply 9): Yes, its a matter of time until our Austrailian friend with his friendly attitude towards the A380, 4 holers in genaral and Airbus will educate us with his lesons again.

Good to hear from you, flyglobal!  

Actually I don't have a 'firm opinion' yet. On the face of it, with Airbus having secured no new A380 orders for the best part of a year, and Boeing only achieving a very few for the B748, the tide does appear to be turning in favour of the 'big twins.' But it's early days yet. We may (but only may) get a better 'fix' on things (particularly in the key area, orders for the 777X) during the Dubai show.

I'm happy to wait till then before I form (or communicate) any definite opinions.

Can't resist adding that I'm happy to help you with English spelling at any time, though; if you feel the need..........  

At least in the cargo business one needs to have 4 engine aircraft with front door access like the 748F, as one can't load the bulky freight through the door at the back.

Quoting Luxair747SP (Reply 14): as one can't load the bulky freight through the door at the back.

Highly relevant point, Luxair747SP - but it remains to be seen whether Boeing will be able to afford to keep the 748 line going for freighters alone. They don't have all that many 748 freighter orders in hand:-

http://en.wikipedia.org/wiki/Boeing_747-8

And - 'same old problem' - the 777 freighter version is selling well too?

Quoting art (Reply 5): I think that once the A351/777-X get uncomfortably close to A388 CASM Airbus can improve A380 CASM by MLU / re-engining / unshrinking.

Airbus also recently stated it doesn't believe the airlines are using the 380 to it's full capacity -- suggesting that airlines can probably stuff another seat per row in Y ala the 777 experience. If done, CASM will increase further

Although 2 vs 4 engines is a fascinating topic for us a-netters, it's of little relevance to the industry. It's simply an outcome of technology and market needs

The max thrust to max weight ratio for civil airliners is about 0.3 (with some variation due to aerodynamics and stuff)
Going on that, and with current engine technology offering a max thrust of 2x 115000lb, the MTOW will be limited to about 350tons
...which is the MTOW of the 77W and 77X. As per reply 12, and correlated with Seat Guru data about Air France, Singapore, Cathay and a few others, with a jampacked 10-abreast cattle class those 350tons translate into about 350 passengers on current 3-class 77Ws, and should mean around 380 passengers on the -X.
As another rule of thumb, for long-haul one could consider that 1ton of MTOW carries slightly more than 1 passenger.

So at present and in the near future, if you want/need to carry more than 400 people in a 3 class configuration, you have to go with a quad (supposing no one builds a trijet, which seems likely)

Obviously, if there is no such market, then quads disappear ! And that is the eternal debat on a-net  
Supposing there is, then in the longer term, what could enable twins to eat up part of the market reserved to quads is if :
- engines makers build engines with thrusts substantially higher than 115000lb
and/or
- airframes become significantly lighter, so that for a same max weight, more of it is dedicated to carrying passengers and the volume needed to house said passengers

I don't really know how much more margin there is for thrust (any engine guru here ?), and engine size is anyway limited by frontal area drag, ground clearance (ldg gear sizes) and structure required to carry the engine weight. As for airframe weight, I don't expect anything spectacular there.
My guesstimate would be that twins could reach 450 seats in 3-class in the next decades

Radical new designs like BWBs could negate all my rules of thumb, but I don't belive in those things at all.
So as I agree with art that there is indeed a developing market for >450seats in 3-class, I think we'll continue to see quads for some time. Unless space travel or teleportation or something unexpected comes along...you never know  

Quoting art (Reply 4): Once a 2 engined 500-650 seat design is developed, yes. Until then A380 will win on CASM.

Today there is no material known to build the blades for such an engine, nor is it clear there ever can be such a material...

Quoting airmagnac (Reply 19): So at present and in the near future, if you want/need to carry more than 400 people in a 3 class configuration, you have to go with a quad (supposing no one builds a trijet, which seems likely) Obviously, if there is no such market, then quads disappear ! And that is the eternal debat on a-net Supposing there is, then in the longer term, what could enable twins to eat up part of the market reserved to quads is if : - engines makers build engines with thrusts substantially higher than 115000lb and/or - airframes become significantly lighter, so that for a same max weight, more of it is dedicated to carrying passengers and the volume needed to house said passengers I don't really know how much more margin there is for thrust (any engine guru here ?), and engine size is anyway limited by frontal area drag, ground clearance (ldg gear sizes) and structure required to carry the engine weight. As for airframe weight, I don't expect anything spectacular there.

The engines can be built bigger, but nobody wants to take the risk on a massive twin with low sales. As such, I think the tube and wing design will always have a small niche for a quad at the top of the range powered by engines that are an offshoot of a big twin engine. Assuming the 77X does well, I can see Airbus bolting TXWBs on the 380 for very little extra dev budget.

It seems that if 4 engine passenger jets have a future at all it's in the mega-capacity niche. For now, the A380 is a workable and efficient solution. As a 747 fan I hoped the 748 would sell more than it has so far.

A factor to be considered is how much the mega-capacity niche will grow. My guess, and it's only a guess; is that the niche will continue to grow at the current pace. Which means there's only room for one player and the A380 is the preferred option by those few airlines that need planes that big. For the great majority of airlines, aircraft like the A330/A350 and 777/787 will more than suffice.

Of course, my airplane enthusiast self wants to see the mega-capacity niche explode, see more A380s and 748s sold and force both Airbus and Boeing to design and build new 4 holer jets. I can dream, right?     

Cheers, Ralph

Quoting art (Reply 4): Until then A380 will win on CASM.

Quoting art (Reply 4): Were that the case, why did they re-order A380's?

I would argue that the A380 does not win on CASM now in EK's fleet. Certainly their 423 seat 77Ws have lower CASM than their 489 seat A380. Even their 3 class 360-seat 77W should have a lower CASM as it weighs 84t less. The 777x won't help this equation.

Generally the A380 'wins' on other things than CASM.

tortugamon

I would say yes, if another 4 holer is designed what would be its purpose?
No one expected that Concord would be the last and only supersonic pax a/c, hard to believe that with engine technology improving so much since the 1960's that supersonic travel is at the same level confined to the military. So with the current engine technology and a/c designs, other than efficiency, does increase size really matter?

In my opinion, how much larger in size do we expect a/c to go, or to put it another way, how many people do we expect to put into one a/c for arrival at a single destination?
My employer still has a travel policy that when a certain size group of staff are travelling to a single destination, they cannot all travel on the same a/c, this usually means different flights and in some cases, different carriers.

.......bout time also. I say bring on the six holers..... 

"Is it possible to cruise with n-1 or n-2 engines?
Are there any altitude restrictions for engine re-lit?
Will it be still economical with n-1 or n-2 engines running?"

IIRC that is what the 727 used to do.

Quoting art (Reply 16): Anyone else share my view?

Yeah, John Leahy..........

Quoting aerorobnz (Reply 10): by which you mean EK has so many on order it doesn't know what the hell to do with them all right?

It is strange how the A380s can be such a problem when they have 3 times as many 77W.

Quoting tortugamon (Reply 22): I would argue that the A380 does not win on CASM now in EK's fleet. Certainly their 423 seat 77Ws have lower CASM than their 489 seat A380. Even their 3 class 360-seat 77W should have a lower CASM as it weighs 84t less. The 777x won't help this equation. Generally the A380 'wins' on other things than CASM.

How to lie with numbers  

Quoting art (Reply 16): All in all I see the A380 cornering much of this niche market so I think there will be quite a few sales to operators specialising in the Chinese and Indian markets (75-150?).

When the only operator in either country wishes they never ordered it and the other country has banned any operator from even operating it in their country it is difficult to see the A380 cornering this market any time soon.  

Despite this, Asia is home to the most A380 (not the ME yet) and all A380 fly to the UK and USA more than anywhere else.

There is no doubt that the growth will be in Asia and the A380 will get a decent share of the market, especially if it is improved upon. However, when both the A350 and the B787 are rolling off the FAL at 10-14/month vs A380 at around ~2.5 it is not difficult to see what planes will carry the majority of the traffic.

tortugamon

The biggest concern I see with a twin engine aircraft the size of an A380 or 747 is ground clearence for the engines. I would think that due to the extra potential height it may add more weight, and complicate the landing gear.

Quoting maxholstemh1521 (Reply 30): The biggest concern I see with a twin engine aircraft the size of an A380 or 747 is ground clearence for the engines. I would think that due to the extra potential height it may add more weight, and complicate the landing gear.

I don't see the engines necessarily causing the issue but rather the length of the aircraft resulting in ground clearance issues.

The 777 for example would have to go out to about 82m (and the 350 even further) to reach a 747 capacity (~460) but the current GE90-115Bs at 128" and 115k thrust should be enough thrust to make the aircraft work and those would not require any changes to the MLG. However, the rotation angle on takeoff could be an issue without further MLG changes.

tortugamon

What I was referring to was once production ends for the A380s and B748s
will either company build another pax version 4 engine widebody plane.

My guess is that after the A380, the next very large airliner (VLA) will be a blended-wing body (BWB) design. Boeing in recent years has done a lot of research with the X-48 UAV to test a number of aerodynamic concepts with BWB, and the result of that research could lead the way to a BWB airliner that could seat just as many people as the A380-800 but with 25% lower fuel burn!  

Quoting RayChuang (Reply 30): My guess is that after the A380, the next very large airliner (VLA) will be a blended-wing body (BWB) design.

Almost certainly. One reason I'm excited about folding wingtips is the huge wingspans of BWBs need some moderation for gate space and taxi way clearance.

Lightsaber

Quoting mia305 (Reply 29): What I was referring to was once production ends for the A380s and B748s will either company build another pax version 4 engine widebody plane.

Lets see how many A-netters will be around when that happens  

The 4 engine widebody is only really needed on a few very long non-stop flights over water or the poles or in/out of certain major and overbooked hub airports like LHR where the volume of pax must be maxed out on each available flight slot. There will come a time when the costs of fuel will substantially reduce he numbers of people who can afford to travel. Indeed they may be numbered but due to economic reality, not technical reality.

Quoting NAV20 (Reply 13): Quoting Luxair747SP (Reply 14): as one can't load the bulky freight through the door at the back. Highly relevant point, Luxair747SP - but it remains to be seen whether Boeing will be able to afford to keep the 748 line going for freighters alone. They don't have all that many 748 freighter orders in hand:-

Needs? Sure. As much as have been built? No way.

I've supervised a few load/unload ops in my time where noseloaders were involved. There is no question that it was a huge convenience and that a good hour or more is saved when loading this way (Along with the aft door that is).

But I can count on one hand how many times it was actually needed. Don't get me wrong, there is a need for it, it's just a lot more here and there than people realize. In all honesty, that need is so small that with adequate maintenance, there probably already are all the 744f, 748f, & 124 airplanes we'll ever need.

Quoting art (Reply 14): As this is leisure travel, I think cost will be the decisive factor in choosing the carrier. I see a good number of carriers using the cheapest mass transit medium available: the A380

? The 380 is not now, nor ever has been, the cheapest way to move PAX. More on the CASM myth later...

Quoting art (Reply 14): I assume a 750 seat A388 could do 1 return trip each day,

Do you know of plans for such a config?

Quoting art (Reply 14): Of course it's a crude calculation.

Nothing crude about it per se. I will admit it's ridiculously optimistic though, as well as completely dismissive of cheaper models available as well as the desires of both travelers and operators.

Again, not crude, but you do need to grow the scope of this "scenario" quite a bit for it to be more realistic.

Quoting JAAlbert (Reply 15): Airbus also recently stated it doesn't believe the airlines are using the 380 to it's full capacity -- suggesting that airlines can probably stuff another seat per row in Y ala the 777 experience. If done, CASM will increase further

It's true. There is nothing like the capacity available actually being used on the market. And yet 380 operators are indeed making money off them despite their very heavy operating costs. This indicates something other than our beloved CASM is at work here.

Quoting airmagnac (Reply 16): (supposing no one builds a trijet, which seems likely)

I can't say whether that's likely or not. But it would be awesome!

Quoting tortugamon (Reply 20): Certainly their 423 seat 77Ws have lower CASM than their 489 seat A380. Even their 3 class 360-seat 77W should have a lower CASM as it weighs 84t less. The 777x won't help this equation.

Quite so. As well as having 2 fewer plants to maintain, and a much lower MTOW to pay to airport authorities, not mention lower staffing costs.

Quoting tortugamon (Reply 20): Generally the A380 'wins' on other things than CASM.

I'm not sure what it's going to take for people here to ditch the A380 CASM mythology, but I'm guessing it's going to be a while. Which is a real shame (yes, I started that sentence with a conjunction), because all of that completely belies what Airlines are really using the 380 for. As a premium class mid-haul to ULH revenue generator, the 380 is second to none. And simply put (there I go again), this has nothing at all to do with CASM, as real airlines generally no-factor that when purchasing airplanes.

Well someone had to bring up the BWB so I will go a little off the deep end too:

The solar impulse flies with four engines and uses zero fuel to fly for 36 hours. It only seats one person and has a max speed of about 43 MPH so it would set travel times back a little bit  

But seriously what if that kind of technology could be perfected on a larger commercial scale? I could see a stripped down aircraft built for efficiency where a very long span might need multiple electric engines because of too much torque on lightweight wings. The Solar Impulse has A340 wingspan afterall. We would travel slower but it would be a lot cheaper. Electric engines could mean no need to carry fuel which would make the plane lighter requiring even smaller engines...and the spiral goes on and on.

How many flights are under two hours; would 50% longer (3 hours) but more than 50% cheaper motivate people? By using smaller airports you could make up the time by not parking a car/security/tsa etc.

Our single aisle aircraft are getting heavier and being made to go further. Lighter, slower, and shorter distances could bring muni airports into play.

Many people think there are about 3 airports in Los Angeles. There are actually more than 30. SBD-SMO anybody? CMA-CLD?

I know its a long shot but I never got my George Jetson flying car and I am not happy about it.

tortugamon

Quoting art (Reply 36): Did you?

Yes. Though it would not have been had that sentence been a question...

Quoting art (Reply 36): Airlines do not consider CASM when buying aircraft?

No A380 would seat less than 650 pax if they did.

They certainly do look at operational cost, and things like PRASMs, but to say that one plane or another is chosen based on CASM is an a.net fiction.

And again, in case I didn't say it in this thread, the 380 needs a stage length of greater than 4000mi, and (not or) a full pax load to break into the top three for CASM. How many routes are currently qualifying there?

Keep in mind that CASM is only at all a useful metric if you are planning on operating a single class configuration. A $15,000 fare F class seat will contribute as much to a CASM figure as a $200 Y class will, which is why it's a BS way to measure an airliner's virtue.

Quoting DarkSnowyNight (Reply 37): Keep in mind that CASM is only at all a useful metric if you are planning on operating a single class configuration. A $15,000 fare F class seat will contribute as much to a CASM figure as a $200 Y class will, which is why it's a BS way to measure an airliner's virtue.

Thank you! I've been trying to point this out in past threads when certain anet folks go on about CASM like it's the most important thing for an airliner. Add to this that CASM is not some constant and varies from route to route with the same distance as airport, nav, pax service charges etc all make quite a difference.

In response to the original post, I don't believe we're going to see a sudden explosion in sales of VLA's (747 & A380). Pax numbers have been doubling roughly every 15 years and yet the narrow body and twin engine wide body sales are what have increased not the VLA's. In addition, pax growth rate is forecasted to continue at the roughly 5% it has been for the past 3-4 decades...most of this growth will be from Asia for the next few years as the USA and EU start to slow down.

The VLA does have its place but its going to be limited to the high capacity routes with limited slot availability (except EK of course which has a very different operating model). However, how many of those are there? Also those hubs will be expanded at some point or have an even bigger hub built close by to relieve the pressure. Add to this that current trends suggest increasing fragmention will continue as well as higher frequency being of preference, both which favour smaller wide bodies for long haul travel. Now these smaller wide bodies are now able to match the cost efficiencies of the VLAs which further limits the use of the VLA as the smaller wide bodies present more flexibility and less risk during down turns in the cycle. You add to this that there is still a lot of scope to cater for pax growth within the twin engine wide bodies e.g. a double daily service from an a333 to a351 will take in an additional 80,000+ pax a year.

I don't think a standard tube and wing aircraft will be produced with more than 2 engines by Boeing or Airbus, except its a different design concept like the BWB or some other version.

I find this argument really interesting, because as a mere passenger rather than an aviation industry insider, it seems to me that the airlines are filling every seat on every plane.

I honestly can't remember the last time I flew on an aircraft that was anything other than jam packed full! This has been A380s, A330s and 747-400s to Asia, Australia, New Zealand and the USA, - it's been A321s, A319s, E195s within Europe, they've always been full.

EK appears to be putting A380s on so many routes, surely they wouldn't do this if people didn't want to fly?

I agree that until planes with two engines and 500 seats become available, four engined aircraft will be needed...

Quoting tortugamon (Reply 26): Quoting art (Reply 16): All in all I see the A380 cornering much of this niche market so I think there will be quite a few sales to operators specialising in the Chinese and Indian markets (75-150?). When the only operator in either country wishes they never ordered it and the other country has banned any operator from even operating it in their country it is difficult to see the A380 cornering this market any time soon.

Bit of a cheap shot, in my opinion! The Chinese case as down to internal politics, and withdrawal of previously agreed rights, all subject to earlier a.net threads. The Indian angle is, well, again, political!

Both will change in time

BTW, Moderators, please change the title to "Are......" instead of "Is..." There are still rules for English, just as there are for ATC, aircraft construction and certification, ........!

Quoting sassiciai (Reply 40): Bit of a cheap shot, in my opinion! The Chinese case as down to internal politics, and withdrawal of previously agreed rights, all subject to earlier a.net threads. The Indian angle is, well, again, political!

I added a   afterward. Doesn't that help?   Regardless, I don't think I stated anything that is untrue regardless of the circumstances for those truths.

Quoting sassiciai (Reply 40): Both will change in time

And that is why I added a time qualification to my comment. Despite there not being much evidence of anything changing imminently, certainly China and India could reverse course.

tortugamon

I, who knows far less than anyone here thinks that everything and everyone's days are numbered!

Isn't it just speculation what will happen? 30 years from now with 30% more fliers, all aircraft frames that are new today will be old. Mankind's needs will change and there is always the unexpected (See World War Z   )

Will a 3 holer ever make a comeback in a totally new way? Could the supersonic limitations be solved in 2043? One thing I bet is that GRU will still be too crowded  

I'm so upset that I will be dead by the time we have aircraft with anti-gravity capability.

Quoting DarkSnowyNight (Reply 37): the 380 needs a stage length of greater than 4000mi, and (not or) a full pax load to break into the top three for CASM.

That is interesting data. Where can we see it?

Quoting Luxair747SP (Reply 12): At least in the cargo business one needs to have 4 engine aircraft with front door access like the 748F, as one can't load the bulky freight through the door at the back.

Certainly, and this market seems well served what with 747-8F, An-124 and a variety of smaller aircraft.

Quoting par13del (Reply 21): In my opinion, how much larger in size do we expect a/c to go, or to put it another way, how many people do we expect to put into one a/c for arrival at a single destination?

Good question. Given city pairs like LHR-HKG currently have over a dozen widebody flights daily, there seems to be demand for very large aircraft.

Quoting par13del (Reply 21): My employer still has a travel policy that when a certain size group of staff are travelling to a single destination, they cannot all travel on the same a/c, this usually means different flights and in some cases, different carriers.

That may be so, but this would hardly negate large aircraft.

Quoting RickNRoll (Reply 23): "Is it possible to cruise with n-1 or n-2 engines? Are there any altitude restrictions for engine re-lit? Will it be still economical with n-1 or n-2 engines running?" IIRC that is what the 727 used to do.

Nope, the 727 did not cruise with an engine off and it is not a good idea for max range. The drag from the windmilling engine would negate any advantages, not to mention lubrication issues on said engine. The only airplanes that routinely shut down engines in cruise are patrol aircraft; increases max endurance.

Quoting RayChuang (Reply 30): My guess is that after the A380, the next very large airliner (VLA) will be a blended-wing body (BWB) design. Boeing in recent years has done a lot of research with the X-48 UAV to test a number of aerodynamic concepts with BWB, and the result of that research could lead the way to a BWB airliner that could seat just as many people as the A380-800 but with 25% lower fuel burn!

This has been talked about for decades but we are no closer to a BWB than twenty years ago. Certainly BWBs have big advantages but the challenges to be overcome for passenger carriage are numerous and substantial, i.e. costly.

Quoting ltbewr (Reply 33): The 4 engine widebody is only really needed on a few very long non-stop flights over water or the poles or in/out of certain major and overbooked hub airports like LHR where the volume of pax must be maxed out on each available flight slot.

The need for more than two engines for diversion reasons is rapidly going away. There are plenty of routes where you have almost hourly widebody flights that are full. There is plenty of market for a VLA, especially in Asia. The question is whether a twin is more profitable for airlines. Skip the extra pax but make a bigger profit on the ones you can pack into your 777/350.

Quoting ltbewr (Reply 33): There will come a time when the costs of fuel will substantially reduce he numbers of people who can afford to travel. Indeed they may be numbered but due to economic reality, not technical reality.

This is by no means a given. Expressions like Peak Oil have been bandied about since at least the seventies. We're not there yet and airliners continue to make large strides in efficiency.

Quoting art (Reply 41): How do you measure an airliner's virtue then? Range, speed, purchase cost?

How many a.nutters find it cool obviously. For this reason, future airliners should be huge three holers with spiroid winglets.

Quoting VC10er (Reply 43): I, who knows far less than anyone here thinks that everything and everyone's days are numbered!

Speak for yourself. I plan to live forever.

Quoting art (Reply 41): How do you measure an airliner's virtue then?

That really depends on the operators' mission profile. FR is not going to have the same needs as KL or EK.

If it really mattered as much as some folks like to think, there would only be A380s (but soon to be replaced by 389s & 779s) for long haul, 753s for mid sector, and Q400s for anything short of 500mi. And there would be NO F, J, or Y+ sections available, since those all harm CASM very quickly.

Quoting art (Reply 41): Range, speed, purchase cost?

All of those things do actually matter, yes. But again, that goes back to what you intend to do with your aircraft.
Are you a vacation vendor or a network giant?

Quoting art (Reply 41): I don't really see the point of developing new aircraft to reduce CASM eg 787 v 767, 777 v 744 if CASM is of little consequence to the buyer.

And neither do the OEMs. They'll develop new types primarily to increase both capability and efficiency, but these are not always hand in glove.

The closest you'll see there to CASM is total operational cost, since it's an effective impossibility to design an aircraft that would deliver great CASM from one airframe across a variety of capability needs and PAX configurations (on the plus side, you won't see anything horrible either).

Quoting art (Reply 41): Nor do I see why OEM's would trumpet fuel burn and operating cost figures for new models compared to existing models if they were not key criteria when making purchase decisions.

Advertizing, to put it simply. It's the same concept that allows auto-manufacturers to trumpet performance numbers on family sedans. Does my Hyundai Sonata ever need to drag race or corner really hard on the way to the beach? From the (online) brochure I looked over before I bought it, you'd sure think so!

Quoting art (Reply 41): How many intercontinental routes are less than 4000 miles?

How many of those seat 650 or more? I did put that in as an And with that, since CASM depends directly on the number of seats as well as distance flown.


How that all regards to quad VLAs...

As I've said before, if the airlines were really interested in driving down their unit (per seat) cost as far as possible (and some are, but they don't operate 380s or 748is), why aren't we seeing 800 seat 380s and 600 seat 748is?

The answer is most likely because in those configurations, QVLAs would never offer real value. Since they do have to fly some distance to drive these unit costs down, it's unlikely that they'd be that attractive to PAX in a high density config for 8+ hour flights. It's also unlikely that airlines would be able to make any money selling tickets at the prices needed to entice enough PAX to make that venture worthwhile. Remember, we have airlines like KE utilizing their 380s in very low density configurations, as this allows them to sell a much higher number of premium seats. Given that long haul and ULH are naturally more attractive this way, it's here that they really make their money. The 380 seats more J class than anything out there or planned, so it's something of a natural for this.

This is all a long winded way of saying that RASM is much more important than CASM. You could have a CASM advantage in the double digits, but if those seats are flying empty, or heavily discounted, it really is just a selling point.

The fact that most 380s out there (if not all), have a significantly lower seating density than possible and still make their money for their operators is (not so) mute testimony to this.


Ok, so there's all that. But why else might CASM not be as important as total operating cost? The answer is that in order to show a real sexy CASM number, we have to no-factor a lot of really important line items from the operational budget of a fleet type.

No aircraft in commercial service is more expensive to land at an airport or cross airspace than the 380. These fees are not inconsequential, and are determined based on MTOW. Fair or otherwise (and I'll admit that one is a whole debate all by itself!), most countries and airports bill this way, don't care a whit whether you're loaded to the gills or operating a ferry sortie. It's all based on MTOW.

We also have maintenance, aka The Red Haired Step Child of commercial aviation. The single most cost intensive part of an aircraft here is powerplants, and not by a little bit either. And the 380 and 748 have four of those. At first we can say that these costs might be a percentage point or two cheaper (per engine) than a twin where things like ETOPS are concerned, as that is a more intensive program. But that goes away again given that ETOPS as a concept has been so successful where safety is concerned that at most airlines and with most Authorities, Quads and Trijets are now subject to these practices as well when conducting ETOPS flights.

Staffing costs will also be higher as well, given that the 380 requires significantly more FAs than a 333, 77W, or 359. One could argue that the 380 has an advantage in that you fly only one of those instead of two of the other, but in practise, that doesn't happen as much as we think. EK, being a good example, will frequently step up a route to 380 from a 77W without altering frequency. So that is a net increase in cost.


For all of those reasons, this is why I find difficult to imagine another Quad Jet coming out, barring the whole BWB thing. In all honesty, I don't even see the 389 becoming a reality as the PIP/IGW updates to the 388 in tandem with the fact that airlines who have them are already not using the "full potential" of existing 388s work against that too.



In any case Art,

It's good that you ask these as it does provide an opportunity to at least try to set the record straight on all this. The 380 is indeed a marvel of engineering, and actually has a lot of advancements you will not find on 787s (not yet anyway). The systems redundancy and and safety margins on that plane are better than anything I've seen to date, and that's from someone who puts his hands on them (and a goodly amount of other types) pretty often. As well, it is a first or second choice to fly on as a PAX, given that the seating configurations are better than just about anything else out there.

I get wrapped up about the CASM thing, because not only is it misleading, but it also belies the real story behind that plane and takes attention away from the very real things that are great about it. It's a lot like saying "The 747 is the best plane in commercial history because it was the first to feature overhead bins in the center section!"

Quoting cmf (Reply 44): That is interesting data. Where can we see it?

Where I work, we use a few somewhat proprietary programs to determine our "best guess" as to what an Operator's costs are. We cannot effectively bid engineering contracts without this ability.

But if you have it, PianoX is a pretty accurate summation of this, and rarely deviates significantly from anything else I've seen. Better still, it's user-friendly enough to manipulate different outcomes based on changes in circumstance or load.

Quoting DTW2HYD (Reply 6): Is it possible to cruise with n-1 or n-2 engines?

Yes, but you will not be able to maintain height and descending to the lower altitude will result in your 3 remaining engines burning more than the original 4. Case in point: BA LAX-LHR.

Quoting DTW2HYD (Reply 6): Are there any altitude restrictions for engine re-lit?

Yes, usually 25K feet or less.

Quoting DTW2HYD (Reply 6): Will it be still economical with n-1 or n-2 engines running?

No, and you will not find a NAA willing to certify it for civilian operations either.

What's the deal with the love/hate relationship with CASM here?

I mean, obviously, if I can take out 10 seats of 100 and put one F seat in there and sell it for 50 times the price, I would do it.

How does it change the fact that comparing CASM of 500 seater and 600 seater is still just as relevant even if I would operate them in 450+5 or 540+6 config. Doesn't mean I suddenly don't care that the 546 seater is 10% per-potential-seat cheaper then 455 seater.

Unless there is an artificial cap such as 189 in 737-900 non-ER, CASM at capacity translate quite directly into CASM in a premium heavy configuration. Even more so in case of VLAs, which have proportionally more weight per passenger seat (in structure and fuel) than smaller jets
(i.e. by removing 10% of 800 people in an A380 I get about 8 tonnes, somewhere about 1.3% MTOW, while removing 10% of 180 people in A320 saves about 1.8 ton, about 2.3% of MTOW -> 1% more weight saving)

Quoting NAV20 (Reply 12): They don't have all that many 748 freighter orders in hand:-

Boeing can still make money even if the rate drops to 5 or 6 a year until the freight need redevelops.

Quoting sassiciai (Reply 39): BTW, Moderators, please change the title to "Are......" instead of "Is..." There are still rules for English, just as there are for ATC, aircraft construction and certification

*** Please use the "suggest deletion" button to communicate this to the Mods.. They don't peruse every thread looking for comments.